Approaches are being developed that use over-the-air or wireless power transmission between a transmitter and a receiver coupled to the electronic device to be charged. Such approaches generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and a receive antenna on the device to be charged. The receive antenna collects and rectifies the radiated power for charging the battery.
Other approaches to wireless energy transmission techniques are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna (plus a rectifying circuit) embedded in the electronic device to be charged.
Remote systems such as vehicles have been introduced that include locomotion power from electricity received from a battery. For example, hybrid electric vehicles include on-board chargers that use power from vehicle braking and traditional motors to charge the vehicles. Vehicles that are use electric power may also receive the electricity for charging batteries from other sources. Battery electric vehicles (BEVs) are conventionally proposed to be charged through some type of wired alternating current (AC) such as household or commercial AC supply sources. Other proposed charging systems include wirelessly charging a battery from a charging device via a wireless field.
To improve efficiency, a wireless charging system for electric vehicles may include transmit and receive antennas aligned within a certain degree. Differences in distance and alignment of transmit and receive antennas impacts efficient transmission of power. Therefore, a need exists for adapting link parameters in a wireless power transfer system in order to improve, among other things, power transfer, efficiency, and regulatory compliance.